1. Field of the Invention
The present invention relates to an adhesive sheet roll for wafer processing, an adhesive sheet for wafer processing, and an adhesive sheet with semiconductor wafer. The present invention also relates to a manufacturing method of a semiconductor device using an adhesive sheet for wafer processing or an adhesive sheet with semiconductor wafer, and a semiconductor device obtained by this manufacturing method. The adhesive sheet roll for wafer processing of the invention is useful as adhesive sheet used for protecting the wafer surface in the grinding process for grinding the rear side of the semiconductor wafer in the manufacturing process of various semiconductors, or adhesive sheet for fixing and supporting for adhering to the reverse side of the wafer in the dicing process for automatically collecting small pieces by pickup method by cutting and dividing the semiconductor wafer into small pieces.
2.Description of the Related Art
In the wafer manufacturing process, generally, the wafer forming a pattern is ground to a specified thickness by back grinding process. At this time, for the purpose of protecting the wafer, generally, the wafer surface is ground by adhering an adhesive sheet as wafer adhesive sheet. When cutting the wafer into individual chips, generally, the wafer surface is diced by adhering an adhesive sheet as wafer protective sheet.
Recently, the wafer is becoming larger in size such as 8 inches or 12 inches, and the wafer is becoming thinner for use in IC card or the like. The adhesive sheet used in such processing is required to be peeled easily after processing the semiconductor wafer, it is proposed to use an adhesive sheet having a radiation curing type adhesive layer capable of lowering the adhesion of the adhesive layer by irradiation with ultraviolet ray or the like. When this radiation curing type adhesive sheet is irradiated with radiation such as ultraviolet ray, the adhesive layer is cured and shrinks, and the adhesion with the semiconductor wafer at the adherent side is lowered.
A radiation curing type adhesive is composed of essential materials including base polymer, radiation polymerizable compound (monomer, oligomer) having carbon-carbon double bond in the molecule with the weight-average molecular weight of 20000 or less, and radiation polymerization initiator, and is prepared by adding proper additives such as crosslinking agent and others. Such adhesive is extremely lowered in the adhesion after exposure to radiation, and a multifunctional compound having two or more carbon-carbon double bonds in molecule is used as radiation polymerizable compound (Japanese unexamined patent publication 60-223139 and Japanese unexamined patent publication 62-059684).
By preparing a radiation reactive polymer by introducing carbon-carbon double bond in the main chain or side chain of base polymer, a technology not using radiation polymerizable compound having two or more carbon-carbon double bonds has been also disclosed (Japanese unexamined patent publication 2000-355678).
It has been a problem, however, for such adhesives of wafer processing adhesive sheets that the reaction progresses gradually during storage from manufacture until use because of the reactive property until the adhesive sheets are cured completely at the time of use. Such phenomenon is caused by gradual progress of radical polymerization chain reaction due to photopolymerization initiator contained in the adhesive composition or residual thermopolymerization initiator used when synthesizing the base polymer.
To suppress such polymerization reaction during storage, it has been proposed to add an additive for inactivating the radical chain reaction such as polymerization inhibitor or antioxidant in the adhesive composition.
However, the polymerization inhibitor or antioxidant is not effective unless contained by a certain amount in the adhesive composition, but if contained too much, the adhesive may not react to cure when using the adhesive sheet, or the paste may be left over on the wafer due to insufficient reaction. Further, if such additives bleed out, the semiconductor wafer itself may be contaminated.